1. Field of the Invention
The present invention relates generally to the field of lighter-than-air ships and more particularly to a airship that uses hydrogen as a lift gas.
2. Description of the Prior Art
Hydrogen airships were in common use in the earlier part of this century and several made numerous transatlantic crossings. The hydrogen airship era ended with the explosion of the Hindenberg in New Jersey. For many years it was believed that the explosion was caused by the hydrogen gas used to lift the ship. Recent investigations have showed that this is much more unlikely than previously thought. In fact, photographs and accounts of the incident seem to indicate that it was the nitro compounds used to make the envelope that were actually burning (possibly later fueled by some of the hydrogen). In any case, it is almost certain that the explosion was ignited by either lightning or electrostatic discharge (ESD).
Airships using helium to lift rather than hydrogen have been used for various purposes since that era. While helium is non-combustive, it is also approximately four times heavier than hydrogen and considerably more expensive (because hydrogen can be made by a simple electrolysis of water). Helium ships such as the Goodyear Blimp and others are very well known and are used for advertising and observation. Helium balloons have been used for observation and communications at high altitudes and have also made trans-oceanic flights.
In the past airships have been at the fringes of aviation with airplanes taking a leading role. However, lately there has been talk about much more use of airships to provide stable observation and communications platforms. For example, scientists in Germany have shown that a fleet of 35 airships, each at an altitude of 25 km (15.5 miles or 82,000 feet) could provide complete communications coverage for the entire European continent for a very low cost personal communications network and for cellular telephone (a single airship costs orders of magnitude less than a communications satellite). These ships, because they operate at lower altitudes than satellites, provide a link power budget gain of over 40 decibels and a greatly reduced signalling delay. In addition, the airships can be brought down anytime for maintenance or upgrade. Satellites, once launched, can be neither upgraded nor repaired (See, e.g., Dirk Giggenbach, “Stratospheric Communication Platforms”, NTZ Magazine of the VDE, November 2002, (published in German)).
Hydrogen offers tremendous advantages as an energy source over hydrocarbon fuels and as a lift gas over helium. As a fuel, hydrogen burns clean with the only bi-product being pure water. As a lift gas, it is 4 times lighter than helium. It can be produced from water by electrolysis with a bi-product of oxygen. In addition, if produced from sea water, bi-products also can include tremendous amounts of recovered metals, halogens, and mineral salts. While it is true that a hydrogen-oxygen mixture is explosive, so is an oxygen mixture of any fuel vapor including gasoline or jetfuel.
In the last few decades hydrogen fuel cells have been developed that produce considerable electric power from hydrogen gas or solid or liquid hydrides. In fact, hydrogen fuel cells running from tanks of hydrogen gas have been used in test buses in Chicago. In addition Honda Motors has just introduced its FCX model which is the first car on the U.S. market to run on hydrogen gas using proton-exchange membrane fuel cells and so-called porous ultracapacitors. The fuel cells used in the FCX produce 78 kW of power and give the vehicle a range of 350 km (217 miles—the vehicle also recaptures stopping energy from braking) (See, “Top Ten Tech Cars”, IEEE Spectrum, February 2003, p. 32).
An airship that uses hydrogen as both a source of lift and a source of energy is badly needed in the art.